Photographic elements having antihalation layer composed of vinylpyridine polymer with vinylpyridine polymer sublayer and outer protective layer



Sept. 7, 1948. p, ALLES 2,448,507

PHOTOGRAPHIC ELEMENTS HAVING ANTIHALATION LAYER COMPOSED 0F VINYLPYHIDINE POLYMER WITH VINYLPYRIDINE POLYMER SUBLAYER AND OUTER PROTECTIVE LAYER Filed Aug. 1, 1946 QZIZIQZ ZZZ Z ZZZZZZ Z EZZ EZZZ ZQ COLLOID SILVER HALIDE LAYER TRANSPARE NTIZED PAPER CLEAR VINYLPYRIDINE POLYMER LAYER VINYLPYRIDlNE POLYMER and ANTIHALATION MATERIAL AINTIABRASION LAYER 'INVENTOR.

FRANCIS PETER ALLES BY fi A TTOR-JEY I Patenfed Sept. i948 UNITED STATES PATENT OFFICE' PHOTOGRAPHIC ELEMENTS HAVING ANTI- HALATION LAYER COMPOSED OF VINYL- PYRIDINE POLYMER WITH VINYLPYRI- DINE POLYMER SUBLAYER AND OUTER PROTECTIVE LAYER Francis Peter Alles, North Plainiield, N. J., as-

signor to E. I. du Pont de Nemours & Company,

Wilmington,

Del., a corporation of Delaware Application August 1, 1946, Serial No. 687,709 Claims. (01. 95-9) Thisinvention relates to photographic elements and, more particularly, to photographic elements bearing a novel, removable, antihalation layer on the reverse side. Still more particularly it relates to photographic elements which have a lightsensitive layer on one side of a support which transmits actinic light and the other side of the support has a composite structure consisting of a colloid layer and an antihalation layer wherein the binding agent is composed of a vinylpyridine polymer and anantiabrasion'layer for said antihalation layer.

, An object of this invention is to provide new ously aifect the sensitivity of silver halide emulsion layers. Yet another object is to provide a used. However, emulsion polymerization is quite useful and bulk polymerization methods are eflective. The polymerization is preferably carried out in an aqueous mineral acid solution or medium in the presence of a peroxy compound catalyst at temperatures from about to 50 C. for a period of ten or less to 200 or more hours. The proportion of mineral acid, e. g., hydrochloric or sulfuric, may vary over a fairly wide range, e. g., from 0.5 to 2.5 mols of acid per mol of vinylpyridine monomer. The resulting solution may. be diluted with water and the solution added to a basic solution,

. e. g., aqueous sodium hydroxide, and the precipitated resin filtered, washed. and dried. A neutralizing agent can be present in the wash water.

The invention is not limited to the use of polyvinylpyridine, including the alkyl substituted polyvinylpyridines, as the binding agent for the an'tihalation materials because copolymers soluble in 1% aqueous acetic acid which contain up to 20%of another polymerizable vinyl or vinyl!- dene compound having a single vinyl group (CH2=C are useful. Suitable compounds for copolymerization with a monomeric vinylpyridine composite antihalation photographic. element which does not deteriorate or become tacky on storage. Still other objects will be apparent from the following description of the-invention. I

In a copending application of David Malcolm McQueen and Clay Weaver, Serial Number 687,708, filed on even date herewith, it is disclosed that the vinylpyridine polymers are eminently well-suited as the film-forming binding agent for the antihalation layer of a photographic element. The layers are not dissolved by the alkaline developer or the water rinse baths used after development; However, they are solubilized by the acid present in and at the concentration usually employed in the ordinary acid photographic processing baths, such as stop baths, acid fixing baths, acid hardening fixing baths, acid bleach baths, reversal bleach baths, etc. The vinylpyridine polymers are readily removable because of such solubility. Moreover, they are removable in acid developing baths.

The vinylpyridine polymers can be made by polymerizing a monomeric vinylpyridine, e. g., alpha-, beta-, or gamma-vinylpyridine or a homologue thereof containing an alkyl radical of one to four carbon atoms in the pyridine ring, in a liquid medium by the aid of apolymerizatlon catalyst. An organic solvent solution can be used if desired in which case inert organic solvents are are styrene, acrylic esters and amides, alphaalkyl-substituted acrylic esters and amides, acrylonitriles and methacrylonitriles.

In making the copolymers there may be used such .materials as methyl or ethyl acrylates; methyl, ethyl, isobutyl, and methoxyethyl methacrylates; methacrylamide and N-methylacrylamide; acrylonitrile and methacrylonitrile; styrene; vinyl naphthalene, and the like or mixtures of two or more of these compounds.

In a preferred aspect of the invention, the polymers of unsubstituted alphaor 2-vinylpyridine or its interpolymers containing 1 to 10% of a different interpolymerizable monomer are used.

' Such polymers are nonwater-soluble, synthetic resins soluble in alcohols, e. g., methyl, ethyl, propyl, and butyl, and mixtures of such alcohols with ketones, e. g., acetone, methyl ethyl ketone, methyl propyl ketone, and methyl isobutyl ketone or in certain chlorinated hydrocarbons, e. g., trichlorethylene. They form clear, light-colored, non-tacky films or coatings which are readily and completely soluble in dilute aqueous acids, e. g., acetic, hydrochloric, sulfamic, sulfuric, phosphoric, and oxalic acids.

The novel photographic elements of this invention consist of a. support which transmits actinic light and has a light-sensitive colloid silver halide emulsion layer on one surface thereof. The other surface has disposed thereon, in order, a layer composed of a vinylpyridine polymer having the above characteristics, next an antihalation layer composed of such polymer which has intimately distributed therethrough an antihalation material which absorbs actinic light, and finally a protective layer. The latter layer may be composed of various film-forming materials. Among the useful materials there may be mentioned waterand alkali-soluble polymers and cellulose derivatives and alginates, e. g., polyvinyl alcohol, sodium cellulose glycollate, ethyl cellulose, methyl cellulose, cellulose acid. phthalate, starch glyoollate, and alginic acids and their watersoluble salts, e. g., alkali metal and ammonium alginates.

The preferred photographic elements of the invention consist of a support which transmits actinic light which carries on one surface thereof a light-sensitive colloid silver halide emulsion layer and on the other side, in order, a thin, clear, polyvinylpyridine sublayer, next an antihalation layer composed of polyvinylpyridine having dispersed therethrough an antihalation material, and finally an antiabrasion layer composed of casein. The resulting elements when constructed with a transparent photographic film base constitute commercially important daylight loading photographic films. These films after exposure can be developed and washed. in the usual manner. The entire backing can be readily removed by treatment in an acid bath as described above.

It has been found that the sublayer of the vinylpyridine polymer aids considerably in the removal of the antihalation material. It prevents staining of the film base by particles of the antihalation material. It has been found that when this layer is omitted that it is often necessary to rub the surface of the film element in order to remove surface discoloration due to particles of antihalation material.

The protective or antiabrasion layer also improves the elements. It prevents the staining of the colloid silver halide layer when the elements are packaged in the form of rolls.

A practical method of making the novel antihalation photographic elements is'as follows: The vinylpyridine polymer is dissolved 'in a water-insoluble alcohol, e. g., methanol and ethanol, etc., in an amount of about 0.25 to 20% is then coated onto the back surface of a photographic support, for instance, a transparent film base or a transparentized paper. The layer is dried by removal of the solvent, e. g., by drying in a current of warm air. Another batch of vinylpyridine polymer is dissolved in a watermiscible alcohol in an amount of 0.25 to 20% by weigh of the alcohol and an antihalation material admixed therewith. Thus antihalation pigments or dyes may be added in the form of small particles and dispersed or milled into the solution. Water-tolerant or spirit-soluble dyes can be added from a solvent solution. The solution is then applied to or coated on the back of a film base by any of the conventional coating methodspe. g., coating from a hopper provided with a doctor blade, dipping, by transfer or bead-' ing rollers, spraying, etc., and the solvent allowed .to exaporate. A layer in the order of 1 to microns is generally sufiicient. However, substantially thicker layers can be made if desired. A light-sensitive layer, e.- g., a colloid silver halide emulsion layer, is then coated on the opposite side of the base.

wherein:

Fig. 1 is a schematic cross-sectional view of a photographic film element bearing a vinylpyridine polymer sublayer, an antihalation layer, and a. protective layer; and

Fig. 2 is a schematic cross-sectional view of a transparentized paper photographic element bearing a vinylpyridine polymer sublayer, an antihalation layer, and a protective layer.

Referring now more particularly to the drawing, the film paper i has composed on one surface thereof a colloid silver halide emulsion layer 2. The rear surface of the base is coated with a thin layer 3 which is composed of a vinylpyridine polymer upon which there is deposited an antihalation layer It, which is composed of a vinylpyridine polymer containing an antihalation material. The outer surface of the latter layer is provided with an antiabrasion layer 5.

The element of Fig. 2 consists of a transparentized paper base 6, which has composed on one surface thereof a colloid silver halide emulsion layer 7. The rear surface of said base is provided with a thin layer 8 which is composed of a vinylpyridine polymer. An antihalation layer 9 is coated on the latter layer. It is composed of a vinylpyridine polymer and an antihalation material. An antiabrasion layer in is coated on said antihalation layer.

The nature of light-absorption characteristics of the antihalation material for the layer will, of course, depend upon the particular characteristics of the emulsion. They are added in sufficient amounts to form an effective density which will stop the passage of the undesired light rays. Halation of blue-sensitive and ortho-chromatic emulsions can be minimized by the use of black and red non-halation layers. Panchromatic emulsions, theoretically, require black non-halation layers, although green and deep blue can be used advantageously. Natural occurring pigments of the above-mentioned colors may be used by this invention since the entire non-halation coating is removed during processing. Metallodye complexes and inorganic, colored compounds are likewise suitable if they are of appropriate colors.

The invention will be further illustrated but is not intended to be limited by the following example. The parts are by weight.

Example A cellulose acetate film base was coated on the back surface with a 1.25% solution of polymerized 2-vinylpyridine in methanol to a thickness of approximately one micron and dried. A 3% solution of carbonblack-polyvinylpyridine in the ratio of 2.75 to 1 by weight in a methanolethanol mixture of equal parts by weight was coated on the latter layer to a thickness of three microns. The particles of carbon black were milled into the solution by grinding in a ball mill for 20 hours. The antihalation coating was over-coated with a solution of the following composition:

' Per cent Casein 2.0 Ammonium hydroxide (20% strength) 2.5 Distilled water 25.0 Methanol 70.5

The daylight loading backing produced by the above procedure is easily and completely removed in weak acetic acid, there is no residual smudge or staining of the base, mechanical brushes orjsponges are not required, and the ing the film in weak acid baths, e. g., acetic or citric acid baths, which are commonly employed as a stop bath between the development and fixationstages of processing.

In general, any dye or pigment which possesses the property of absorbing actinic light, of being readily dissolved'or destroyed in ordinary photographic ba'ths, and of not injuring such baths may be used. The dye or dyes to be used in any specific instance are primarily determined by the light-sensitivity of the emulsion. Such emulsions areusually gelatin silver halide emulsions which contain sensitizers, such as cyanine, carbocyanine, pseudo-cyanine, cyazine bases and salts. That is, it must be absorptive of light of the wavelengths to which the emulsion is sensitive. In general, the dye should be added in an amount sufiicient to give a photographic density of 0.2 to 0.8 or the amount of dyed layer should be suflicient to give such a density. When added from ethanol, etc., a very fine subdivision of the dye in the layer is obtained. As examples of additional useful dyes, mention is made of Auramine (C. I. 655) Helianthin (C. I. 142, 14.6) Brilliant Yellow S (C. I. 144) -=Chrysoin (C. I. 148) The color index number (0. I.) referred to above are identified asfollows: Society of Dyers & Colourists Colour-Index, edited by F. M. Rowe, D. 80., F. I. C., First Edition January 1924, published by The Society at the General Offices, 30 Pearl Assurance Buildings, Bradford, Yorkshire.

The invention is not limited to the use of cellulose ester film bases but may be used with practically any transparent film. The polyvinylpyridine layers are adherent to various other film materials, e. 3., polyamides, cellulose nitrate, polyvinylacetals, cellulose propionate, cellulose mixed esters, cellulose ethers, vinyl chloride and copolymers, styrene, acrylonitrile and copolymers, polyesters, vinyl acetate and copolymers, vinyl fluoride and copolymers, polyvinyl alcohol, transparentized paper, etc.

This invention has the advantage that a nontacky antihalation layervwhich is insoluble in water or alkaline solutions but is readily soluble in dilute acid baths may be quickly prepared. A further-advantage is the fact that stable, non-' tacky, non-reacti antihalation layers may be easily prepared. Thus film's may be tightly rolled up with the antihalation layer in direct contact with the emulsion layer and stored for 1225, periods of time without any detrimental e1- As many widely different embodiments of this invention can be made without departing from the spirit and scope thereof, it is to be understood that the invention is not to be limited ex- V cept as defined by the claims.

What is claimed is:

1. A photographic element comprising a support which transmits actinic light, a light-sensitive colloid silver halide emulsion layer onone surface of said support and on the other surface of said support, in order, a clear layer composed of a water-insoluble vinylpyridine polymer which is soluble in 1% aqueous acetic acid, an antihalathin layer composed of such a vinylpyridine polysurface of said support and on the other surface v of said support, in order, a clear layer composed of a water-insoluble vinylpyridine polymer which is soluble in 1% aqueous acetic acid, an antihalation layer composed of such a vinylpyridine polymer which is soluble in 1% aqueous acetic acid and contains an antihalation material, and an antiabrasion layer composed or casein.

3. A photographic film element comprising a transparent film base, a light-sensitive colloid silver halide emulsion layer on one surface of said film base and on the other surface of the film base,'in order, a. clear polyvinyipyridine layer, an antihalation layer consisting of polyvinylpyridine which contians an antihalation material,

and an antiabrasion layer composed of a watersoluble film-forming material, said polyvinylpyridine being water-insoluble but soluble in- 1% aqueous acetic acid.

4. A photographic film element comprising a transparent film base, a light-sensitive colloid silver halide emulsion layer on one surface of said film base and on the other surface of the film base, in order, a clear 2-vinylpyridine polymer layer, an antihalation layer consisting of 2- vinylpyridine'polymer which contains an antihalation material, and an antiabrasion layer composed of a water-soluble, film-forming material. said 2-vinylpyridine polymer being water-insoluble but soluble in 1% aqueous acetic acid.

5. A photographic film element comprising a transparent film base, a light-sensitive colloid silver halide emulsion layer on one surface of said film base and on the other surface of the film base, in order, a clear 2-vinylpyridine polymer layer, an antihalation layer consisting of 2- vinylpyridine polymer which contains an antihalation material, and an antiabrasion layer composed of water-soluble casein, said 2-vinylpyridine polymer being water-insoluble but soluble in 1% aqueous acetic acid.

FRANCIS PE'I'ER ALLES.

REFERENCES crrap 1,939,171 Hickman Dec; 12, 1933 2,182,794 Dawson Dec. 12, 1939 

